The coins and dapps being developed will not all be useless, and they will get scalability:
https://twitter.com/EliBenSasson/status/1161007928733831169
Then they'll have a lot of users. The failure to see that is a failure of imagination, or worse still, a lie intended to try to discourage people from adopting Ethereum.
Also, DeFi dApps on Ethereum like Maker already have significant amounts of capital locked up in them in the aggregate, which is a statistics that you can't simply explain away.
[The entire crypto-asset being built on Ethereum](https://coinmarketcap.com/tokens/), imagine the possibilties.
But what use would decentralizing finance and putting on the blockchain ever have, right? You'd prefer a centralized financial system, just like every other anti-Ethereum advocate.

well of course - financial code comes from centralized entities which have been polished over decades. smart contracts are brand new type of code and anyone can make a contract. there is no barrier to entry.

Blockchain-based smart contracts are a new technology, so this is to be expected, and wouldn't expect Ethereum to be any worse in this regard than other cryptocurrencies.
Ethereum also has more formal verifiers being built for it than any other platform I've seen, like Microsoft's new Solidity formal verifier, VeriSol:
https://www.microsoft.com/en-us/research/project/verisol-a-formal-verifier-for-solidity-based-smart-contracts/
And the number of security features being added by third parties is consequence of how much is being developed on it.

monthly is a really poor way to measure this change, a developer might not have a commit pulled to master every month, on the timescales these projects are around for there is no good metric to determine change in number of developers

disagree, it can take awhile for a developer to have their commits merged into master like i said before, plus not every contribution is a code contribution (some contribute purely on discussions and theory)

regardless, amount of developers on a project doesn't mean the project magically becomes better than a project with less developers
there's a lot of shitty developers out there who will gunk up even the best code audit processes with their drivel

It depends. People work on local copies upstream on their own repos, then when they are complete they do a merge request. It's at that point that you see their dev activity as it was approved. If you are tracking the core repo only you may have very little idea of what's actually happening in the moment. At least that's how my 10 years of github development have worked at every company/project..

Maker and BAT are counted as separate projects here yet they are Ethereum-based, indicating this is not counting all of the developers in the Ethereum ecosystem.

4X higher than the most active cryptocurrency and 18% of all crypto developers is impressive but I suspect the real number is much higher and the majority of developers in cryptocurrency are working on Ethereum or a Dapp built on Ethereum.

Welcome to something called network effects. Even disregarding network effects, the fact is BinanceChain is not really a competitor to Ethereum because it is permissioned/centralized so cannot be a base layer protocol for asset registry and exchange like Ethereum.

The study is about all cryptocurrencies and specifically lists Bitcoin's developer count, dollars transacted per developer, etc. It's definitely plenty about Bitcoin.
Of course it happens to make Ethereum look *better*. But then again, Bitcoin shouldn't be opposed to facts that aren't positive... Riiight?